Conventionally, a backlight source used in a Liquid Crystal Display (LCD) apparatus has a spectrum containing a large amount of high-energy short-wave blue lights at various irregular frequencies. As shown in FIG. 1, the wavelengths of visible light range from 380 nm to 780 nm, among which the wavelengths of blue light lie mainly between 430 nm and 450 nm. Blue light also contains a portion of ultraviolet light. As shown in FIG. 2, ultraviolet light will penetrate the cornea and lends and reach the retina, which will accelerate oxidation of cells in the macular area of the retina. Excessive radiation of ultraviolet light may cause damage to visual cells and thus the eyes.